This invention relates to a device for cutting from bar stock workpieces upon which several machining operations have been performed, and more particularly to a rotary saw cutoff device for use in the confined machining area of automatic screw machines and which does not interfere with or limit the number of work stations with which the machine was designed to be operable.
Automatic screw machines are complicated metal cutting machines designed to perform multiple turning operations on a plurality of workpieces simultaneously. Typically, such a machine involves a rotary stock holder which is adapted to hold several pieces of elongated bar stock and feed it in a predetermined fashion both rotationally from one work station to another and also axially, so that the several machining operations for which the machine was designed can be performed on the bar stock to form the desired parts. Opposed to the rotary bar stock-carrying structure and disposed on the opposite side of the machining area are a plurality of toolholding devices intended to hold such tools as cutters for conventional turning operations, screw thread cutters, drills, reamers, borers, and the like. The machine is intended to be capable of performing sequentially a series of turning, boring, drilling, reaming, or other typical such operations on a workpiece as the workpiece is rotated from one work station to another. Such machines commonly have six work stations and six bar stock holders, but they can have as many as sixteen work stations and bar stock holders or as few as two.
One of the necessary operations in such an automatic screw machine is the step of severing the machined workpiece from the remainder of the bar stock after a predetermined number of machining operations have been completed. In the past, such cutoffs were effected by stationary cutoff tools which were configured similar to a standard tool for turning except they typically had a width of from about 0.090 inches to about 0.125 inches. As a result, that width of material corresponding to the cutoff tool width became waste, and thus there was an impetus to provide cutting devices having thinner widths, which would result in less waste material and would thereby permit a greater number of parts to be made from a given length of bar stock. One such approach is described and illustrated in U.S. Pat. No. 3,598,005, which discloses the use of rotary saw blades of relatively narrow width, the saw blades therein disclosed having extremely narrow widths of 0.032 inches or less. Similarly, U.S. Pat. No. 3,596,545, shows an automatic lathe incorporating a rotary saw cutoff device, the machine there disclosed being capable of handling and operating upon only a single workpiece.
Despite the fact that the prior art discloses narrow width rotary saws as desired cutoff devices for parts made from bar stock in order to reduce waste material and thereby provide more parts per unit length of bar stock, the prior art devices are so configured that they are rather bulky, or they include driving arrangements which severly limit their applicability and virtually preclude their use on commonly utilized automatic screw machines unless space is made to accommodate their bulk. When such space is provided, it usually requires sacrificing a work station in order to permit the prior art devices to be attached to and utilized with the machine. Consequently, there is a need for a rotary cutoff saw arrangement which is significantly less bulky than the prior art devices and which can be utilized on existing automatic screw machines without modification of the machine itself or its parts, and without sacrificing the number of machining operations of which the machine is capable, in order that the machine can be utilized to its full design capacity.